Telecommunications services are usually offered by several service providers. For example, such a service may be used in order to set up a communications connection between several users (e.g. a telephone conversation between mobiles or a multimedia session between two or more terminals or PCs). In this case, each subscriber may have concluded a contract with a different service provider. In current services it is usual for the service provider of the initiator (e.g. the caller or the A-side) of the communications connection to determine the price and charge the A-side accordingly. The other subscribers are not usually charged. The A-side service provider pays a compensation amount to the B-side service provider, which is determined by bilateral agreements that are additionally subject to regulation (billing).
This fee charging and billing system is too rigid for modern communications services, for example for video telephony, where—for example—a video channel may be subsequently added to or removed from the audio channel not only by the A-side, but also by the B-side. In addition, it is also useful to have a unidirectional video stream in parallel to the bidirectional audio stream. A more flexible fee charging system must permit fees to be charged on both the A-side and the B-side. For example, the B-side may be charged for a video stream by its service provider even if the audio stream has been set up and paid for by the A-side. It is also conceivable that the A-side and B-side may wish to share the communication costs, e.g. both paying for the outgoing unidirectional streams. This means that the fee charged may be different for each call.
Furthermore, in modern communications architectures the network operator often makes only the raw network resources available, while the actual communications services are provided by the service provider (separation of network and service providers). In this case, several network operators and several service providers may be involved when a communication service is used. The income received from the users must then be shared between the network operators and service providers involved (billing problem).
The fee charging problem is solved only to a very limited extent using conventional communications networks. For example, IN architecture permits more flexible fee charging for special services (freephone, premium rate, etc.). This flexibility is at the cost of complex protocols yet is nevertheless inadequate for a multimedia communication service.
The billing of services within and between the operators and providers is done mainly by generating data records for each call. These contain—among other things—only call data, but no information about allocation of costs between the service users. Calls with unusual cost allocation (e.g. collect calls) must be processed in other ways, including manually by call centers.